Rotor position selection mechanism

ABSTRACT

The invention provides a rotor position selection mechanism for stopping rotary motion of one or more rotors or print wheels in a print head at desired angular positions each corresponding to a character on the rotor which is required to be printed. The rotor has a group of recesses positioned on a reference grid and located on the rotor so that as the rotor revolves,each group of recesses passes a set of feelers whose positions can be selected to correspond to any one of the patterns of recesses. In operation the positions of the feelers are set to represent a selected code word corresponding to one of the characters in the print wheel and a catch operated by all the set feelers sensing all the recesses on the rotor corresponding to the selected code word moves into a hole in the rotor to arrest its motion. Several rotors or print wheels may be provided, each with an associated group of feelers and a common setting mechanism may be used to set each group of feelers to a different selected code word so that a line of print may be formed by the print wheels being arrested at positions corresponding to the selected code words.

[451 Aug. 21, 1973 ROTOR POSITION SELECTION MECHANISM {57] ABSTRACT [75 Inventor: Kurt Ehrat, Zurich, Switzerland The invention provides a rotor position selection mech- 73 l Asslgnefii clba'celgy Basel, swltzel'land anism for stopping rotary motion of one or more rotors [22] Filed: Oct 19 19-70 or print wheels in a print head at desired angular positions each corresponding to a character on the rotor PP 31,778 which is required to be printed. The rotor has a group of recesses positioned on a reference grid and located [30] Foreign Applicatkm Priority Data on the rotor so that as the rotor revolves,each group of O 23 1969 s I d l5829/69 recesses passes a set of feelers whose positions can be was! an selected to correspond to any one of the patterns of re cesses. In operation the positions of the feelers are set 2? 5 340/373 to represent a selected code word corresponding to one i R 373 R of the characters in the print wheel and a catch oper- 1 0 care ated by all the set feelers sensing all the recesses on the rotor corresponding to the selected code word moves [56} References cued into a hole in the rotor to arrest its motion. Several ro- UNKTED STATES PATENTS tors or print wheels may be provided, each with an as- 2.7l7,980 9/!955 Taylor 340/316 sociated group of feelers and a common setting mecha- 2,723.39l ll/I955 Hailey 340/316 nism may be used to set each group of feelers to a different selected code word so that a line of print may be e formed by the print wheels being arrested at positions 3,28l,8l9 10/1966 Muller ,r 340/316 corresponding to the selected code words Primary Examiner-Harold I. Pitts 12 C'aims, 8 Drawing Figures Attorney-Pierce, Scheffler & Parker 1 l8a l8f 1O 13arl3f l5 sa sf e f Mia-16f 11 I y -r v I Y 12a-12f I ,3 7 d za if E l|ll lllllil|li lt illi ililll llllllllllll l i w u" 4 H13}, r. ill-ll -ll l ll IPlll ll ll ll- H] r n 'll l l r, r E

ROTOR POSITION SELECTION MECHANISM The invention relates to a rotor position selection mechanism for arresting the rotary motion of rotors at selected angular positions, wherein each selectable angular position is marked on each rotor by a codeword adapted to be mechanically detected by a sensing device comprising mechanical feelers which upon detecting the selected code word on the revolving rotor activate means for stopping the rotor.

It has already been proposed in British Patent Specification 998,909 to provide feelers in the form of electrical switch contacts which are connected to a logic circuit. The different positions that the contacts take as the rotor revolves represent the different code words marked on the rotor. The position of the contacts are continuously tested in the logic circuit for agreement with a required code word. When such agreement is established an electromagnetic catch is actuated which engages the rotor and stops it.

However according to the present invention each code word comprises a like number of marking elements and the different code words are identified by their marking elements being positioned in a reference grid that is the same for all code words. The feelers of the sensing device can be set to specific positions in a corresponding reference grid in such a manner that when a code word on the rotor agrees with a selected code word all the feelers respond simultaneously and cause a catch which is coupled to all the feelers mechanically to engage the rotor and arrest it.

More particularly, in accordance with the present invention, the rotor position selection mechanism for arresting the rotary motion of the rotor (or rotors) at selected angular positions, each corresponding to a character on the rotor which is required to be printed comprises a plurality of groups of elements in which on each rotor the elements in each group are positioned to define a different code word, and the groups are positioned about the rotor at predetermined angular positions. The number of elements in each group are the same and the elements in each group are positioned on a notional grid identical for all groups in such manner that each element can occupy one of two.predetermined positions. Each code word is mechanically detected by a sensing device mounted adjacent each rotor which comprises a group of mechanical feelers which are set at positions representing a selected code word for engagement only with the corresponding group of elements on the rotor representing the code word which has been selected. Upon engagement of all of the feelers in a group which have been set to a selected code word with the corresponding group of elements on the rotor representative of that code word, a catch coupled to the feelers then functions to engage and arrest the motion of the rotor.

A preferred embodiment of the invention will be more particularly described with reference to the accompanying drawings in which FIG. 1 shows a rotor position selection mechanism in accordance with the present invention;

FIG. 2 is a section taken on the line Il-II in FIG. 1;

FIGS. 2a and 2b are two examples of codes used on the rotors shown in FIGS. I and 2;

FIGS. 3a and 3b are each a section taken on the line III III in FIG. 2, showing two different operating states of the feelers;

FIG. 4 is a section taken on the line IV- IV in FIG. 3a and FIG. 5 shows in more detail a feeler used in the mechanism of FIG. 1.

Referring first to FIG. 1 a plurality of indicating rotors 2 are provided on a common drive shaft 1; one indicating rotor 2 being provided for each character in a display line. In the illustrated example the line comprises 44 characters and there are therefore 44 indicating rotors.

Each indicating rotor 2 bears on its periphery all the characters that are to be indicated, such as numbers or letters, and it is frictionally mounted on the continuously revolving drive shaft 1. The indicating rotors 2 are preferably plastic injection mouldings. By suitably shaping their central hole the required friction between the rotors and the drive shaft can be generated without the provision of additional frictional means. A masking plate 3, which may form part of an instrument casing, contains a window 3s through which a single line of characters on the indicating rotors can be displayed. Input terminals 6a to 6f permit electrical signals, preferably pulse-shaped signals which correspond to the text that is to be displayed, to be fed into the instrument and, via a mechanism that will be later described, to set banks of feeler levers 4a to 4f of which one bank is associated with each indicating rotor.

With reference to FIG. 2 each character A, B, C, D, etc., on the circumference of the rotor is associated with a mechanically detectable code word comprising elements a to f positioned on a radial reference line. As shown in the drawing the code is a six element code having elements a tof. The number of coding elements may be varied according to the number of characters to be identified. If there are relatively few characters for display, say only digits, a four-element code would be sufficient; if there are more characters a sevenelement code could be provided. Each code element a tofcan be a logic 0" or a logic L". In contradistinction to a punched tape in which the distinction between 0 and L is represented by the presence or absence of a hole, the distinction between logic 0 and I" logic L in the present code is represented by a difference in the position of the code element in a reference grid. The elements a to f of each code word can occupy on the reference grid A, B, C, ./a', b, c one of two positions on either side of a radial line A or B and so forth or on either side of a circular line a or b and so forth. As shown, the elements of the code are recesses which will be hereinafter likewise referred to by the references a to f. I

For instance, in FIG. 2 and FIG. 2a, the radial reference line A has the code word OLLOLO represented by circularly offsetting the recesses a to f provided respectively along the circular reference lines a, b, c to the right and left of said radial reference line A, logic 0 corresponding to a recess offset to the left (recesses a,d, and logic L to a recess offset to the right (b,c,e).

In the modification illustrated in FIG. 2b the same code word OLLOLO is represented by radially offsetting each of the recesses a to f from the circular reference lines a to f respectively, along the radial reference line A.

It will also be understood from FIG. 2 that a sensing device having mechanical feelers 4a to 4f is mounted adjacent the rotor 2 so that the feelers engage code element or recess a to f. All these feelers 4a to 4f are slidable longitudinally in relation to a common leaf spring and are mounted so that they cannot rotate. The leaf spring 5 presses the feelers downwards so that their right hand ends in the drawing are forced to ride on the side face of the indicating rotor 2 into and out of the recesses a to f. The feelers 4a to 4f being longitudinally displaceable can occupy two positions corresponding to the two positions of the code elements a to f. In the case of the code shown in FIG. 2b the feelers would not be longitudinally but transversely displaceable, i.e. radially with respect to the indicating rotor 2. The leaf spring 5 is firmly held at its rear end in the instrument casing, and it bears resiliently on the feelers 4a to 4f. The leaf spring 5 constitutes an arresting catch and for this purpose its forward end is provided with a nib which faces the side of the indicating rotor 2. A plurality of holes 7 is formed in the rotor which the nib can engage to arrest the indicating rotor instantaneously. However, the nib 20 cannot drop into engagement with a hole unless all the feelers 4a to 4f have sunk into a recess a to f simultaneously. This state of affairs will not arise unless a code word on the indicating rotor 2 agrees with a code word set up by the feelers 4a to 4f and registers therewith. When the leaf spring 5 engages the indicating rotor 2, the latter will be arrested in the desired position. The drive shaft 1 will continue to revolve by overcoming the friction between the stationary rotor 2 and the shaft 1. If the feelers 4a to 4b are set to a fresh code word, at least one feeler will be lifted out of its recess(a to j), raising the leaf spring 5 and disengaging its nib from the associated hole 7. Consequently the indicating rotor is released to continue its rotation until a fresh code word to which the feelers have been set registers with a corresponding code word on the revolving indicating rotor 2.

FIGS. 3a and 4 illustrate the leaf spring 5 in a disengaged position, whereas FIG. 3b shows the spring in engagement. In FIG. 3a the feelers 40, 4c, 4d and 4f have dropped into corresponding recesses, a, c, d and f in the side of the indicating rotor 2, but the feelers 4b and 4e cannot drop into recesses because the selected code word does not correspond with the code word with which the feelers are in register. The feelers 4b and 4e prevent the leaf spring 5 from dropping into engagement with the hole 7 so that the indicating rotor 2 will continue to revolve. In FIG. 3b all the feelers 4a to 4f have dropped into corresponding recesses a to f and they thereby permit the leaf spring 5 to move towards the rotor 2 and its nib 20 to engage the associated hole 7, thereby arresting the indicating rotor 2.

The leading ends of the feelers 4a to 4f are preferably downwardly deformed as shown by the feeler 4a in FIG. 4. The skid-like shape and the resilience of the arcuate configuration ensure that the feelers will ride into and out of the recesses without much noise. Moreover, this form of construction is easy and inexpensive to produce, particularly when the feelers are made of spring wire.

In an alternative embodiment shown in FIG. 5 the feelers 4a to 4f are so held in holders 8a to 8f affixed to the leaf spring 5 that they cannot severally engage the recesses a to f in the indicating rotor 2, but only jointly with the leaf spring 5 when their positions agree with the code word with which they register.

Again referring to FIG. 1 the mechanism for setting the feelers 4a to 4f will now be described in greater detail. a motor-driven feed screw 10 carries a carriage 11 which can be traversed by the feed screw 10 across the entire assembly of indicating rotors 2 in the direction of the reading line. The carriage 11 carries six levers 12a to 12f of the bell-crank type. One arm of each lever, for instance 12a, is adapted to co-operate with the ends of associated feelers 4a in a line and to displace these feelers 4a from the one .into the other position, (downwards in the drawing). The feelers in one line are consecutively set in selected positions corresponding to code words as the carriage l 1 traverses in the direction of the arrow Pf. The other arm of each lever 12a to 12f is attached to a cord 13a to 13f, each cord being taken over a first return roller 14a to 14f and then over a second common return roller 15 back again to the carriage to which the other end of the cord is likewise attached. Interposed between the two ends of each cord is a tension spring 16a to 16f. Return rollers 14a to 14f are rotatably mounted on the ends of armatures 17a to 17f of a plurality of electromagnets. The other ends of the armatures are mounted on a hinge which is fixed in the instrument casing. The armatures 17a to 17f are each deflectable by a different one of electro-magnets 18a to 18f in such a way that excitation of a magnet will cause the associated armature to be deflected from its position shown in the drawing into a position in which it is in contact with the magnet. When exciting current is removed, armatures 17a to 17f are released and pulled back into their positions of rest by corresponding springs 16a to 16f. The electro-magnets 18a to 18]" may, for example all be connected in parallel through switches 6a to 6f respectively to a voltage source U. According to the position of the switches 60 to 6f the magnets will thus be energised and de-energised. The switches 6a to 6f may be embodied in gate circuits. As the armatures 17a to 17f move to and fro the bell-crank levers 12a to 12f and hence the feelers 4a to 4f are set. For the purpose of resetting the feelers the carriage 11 carries a restoring element 19 which first restores all the marking elements 4a to 4f totheir upper positions (position of rest) when the carriage 11 traverses in the direction of the arrow Pf.

When a line is about to be written the carriage 11 will be located at the beginning of the line, i.e. in FIG. 1 at the left hand end. The electrical code word corresponding to the first character that is to be displayed is applied to the magnets 6a to 6f which move the bellcrank levers 12a to 12f to set the feelers 4a to 4f of the first indicating rotor 2 to either one of their two positions. As the carriage l l is traversed by the continuous rotation of the feed screw 10 to the second indicating rotor the magnets 6a to 6f receive the coding pulses of the second character that is to be displayed. In this way one character after the other is stored in the groups of feelers 4a to 4f. When a line begins to be written all the indicating rotors 2 are continuously rotated and the desired text will therefore appear in the displaying window 3s of the mask 3 like the text produced by a typewriter. As soon as one line has been set the carriage 11 can be returned to the starting position by a rapid return traverse. The feelers may be very light in weight. For instance, they may be made of 0.5 mm diameter steel wire. Since the deflection paths of the feelers may also be extremely small (about 2 mm) high, setting speeds of about 10 ms and less per indicating rotor can be achieved. A complete line of feelers for indicating rotors therefore requires only about 0.8 secs. The indicating rotors may be driven relatively slowly, say

one revolution in 0.7 seconds and nevertheless permit a complete line to be set and indicated in about 1.5 seconds.

For the desired compact design of the indicating instrument it has been found useful for the feelers 4a to 4f to co-operate with the sides of the indicating rotors 2. This permits the character spacing in a reading line to be as small as 2.5 mm. Moreover, in the interest of compactness it has been found that if the code words on the sides of the indicating rotors lead or lag the peripheral characters by a quarter revolution, the setting mechanism for the feelers 4a to 4f can be very conveniently located behind the indicating rotors.

The described mechanism is naturally not intended to be limited to indicating registers but can also be applied to printing heads. In the latter case the indicating rotors will be replaced by type wheels and these may contain two sets of characters around their peripheries, one for visual reading and one for simultaneous printing.

What is claimed is:

1. A rotary position selection mechanism for arresting the rotary motion of at least one rotor at selected angular positions comprising a shaft; at least one rotor mounted on said shaft for rotation therewith; a plurality of groups of elements, the elements in each group being positioned to define a different code word and the groups being positioned about said rotor at different predetermined angular positions, each code word being adapted to be mechanically detected, the number of elements in each group being the same and the elements in a group being positioned on a notional grid so that each element occupies one of two predetermined positions, said grid being the same for all groups, a sensing device mounted adjacent said rotor, said sensing device comprising groups of mechanical feelers, means for setting said mechanical feelers at positions representing a selected code word for engagement with a group of elements on said rotor representing said selected code word; a catch operable by said mechanical feelers engaging that group of elements representing said selected code word to arrest rotational motion of said rotor; said mechanical feelers being deflected by corresponding ones of said elements and said catch being coupled mechanically to said feelers so that only upon delfection of all said feelers resulting from sensing those elements representing the selected code word the catch is operated to arrest motion of said rotor.

2. A mechanism according to claim 1 wherein said two predetermined positions are symmetrically located on each side of a radial reference line indicating the angular position of the rotor with reference to a datum position.

3. A mechanism according to claim I wherein said two predetermined positions are symmetrically located on each side of a circle whose centre is coincident with the axis of said shaft.

4. A mechanism according to claim 1 wherein said rotor is shaped to define a plurality of holes, each associated with a different one of said groups of elements and said catch includes a nib for engaging said holes to arrest motion of said rotor.

5. A mechanism according to claim 4 wherein each said mechanical feeler comprises a lever, said lever being mounted in a single plane, and said catch comprises a leaf spring one end of which is fixed and the opposite end having thereon said nib which bears against all said levers.

6. A mechanism according to claim 1 wherein said rotor is shaped to define recesses forming said elements.

7. A mechanism according to claim 5 wherein said rotor is shaped to define recesses forming said elements and an extremity of each said lever has a return bent portion for engaging a corresponding recess in said rotor.

8. A mechanism according to claim 1 including means frictionally mounting said rotor to said shaft.

9. A mechanism according to claim 1 including a plurality of rotors, each having groups of elements thereon, the elements in each group being positioned to define a different code word and the groups being positioned about said rotor at different angular positions, and a plurality of groups of mechanical feelers, each group being associated with a different rotor; wherein said setting means includes a plurality of setting members, one for each member of a group of mechanical feelers and means for moving said setting means past each group of mechanical feelers to set the members in each group into predetermined positions for engaging elements on the associated rotor representing a selected code word.

10. A mechanism according to claim 9 wherein said mechanical feelers comprise levers and including means mounting said setting members to engage one end of said levers to move them from a first to a second position.

1 1. A mechanism according to claim 10 wherein said mounting means includes means for setting said mechanical feelers prior to them being set by said levers.

12. A mechanism according to claim 9 including a plurality of electric solenoids, having armatures each coupled to a different one of said setting members, and means for energising said solenoids in different combinations corresponding to different code words to cause said setting members to set the mechanical feelers in a group to predetermined positions to represent a selected code word.

TJNTTTD STATES PATENT oTTTcT TCERHWC/WE @F @QRREQNQN Patent No. 3,754,242 Dated g t 21, 1973 Inventoflg) Kurt Ehrat It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 11, line 2, change "setting" to resetting Signed and sealed this 20th day of November 1973.

(SEAL) Attesti EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attestlng Officer Acting Commissioner of Patents ORM PC4050 (10-69) uscoMM-oc 60376-P69 US. GOVERNMENT FRI HUNG OFFICE 15GB 0-868-3. f 

1. A rotary position selection mechanism for arresting the rotary motion of at least one rotor at selected angular positions comprising a shaft; at least one rotor mounted on said shaft for rotation therewith; a plurality of groups of elements, the elements in each group being positioned to define a different code word and the groups being positioned about said rotor at different predetermined angular positions, each code word being adapted to be mechanically detected, the number of elements in each group being the same and the elements in a group being positioned on a notional grid so that each element occupies one of two predetermined positions, said grid being the same for all groups, a sensing device mounted adjacent said rotor, said sensing device comprising groups of mechanical feelers, means for setting said mechanical feelers at positions representing a selected code word for engagement with a group of elements on said rotor representing said selected code word; a catch operable by said mechanical feelers engaging that group of elements representing said selected code word to arrest rotational motion of said rotor; said mechanical feelers being deflected by corresponding ones of said elements and said catch being coupled mechanically to said feelers so that only upon delfection of all said feelers resulting from sensing those elements representing the selected code word the catch is operated to arrest motion of said rotor.
 2. A mechanism according to claim 1 wherein said two predetermined positions are symmetrically located on each side of a radial reference line indicating the angular position of the rotor with reference to a datum position.
 3. A mechanism according to claim 1 wherein said two predetermined positions are symmetrically located on each side of a circle whose centre is coincident with the axis of said shaft.
 4. A mechanism according to claim 1 wherein said rotor is shaped to define a plurality of holes, each associated with a different one of said groups of elements and said catch includes a nib for engaging said holes to arrest motion of said Rotor.
 5. A mechanism according to claim 4 wherein each said mechanical feeler comprises a lever, said lever being mounted in a single plane, and said catch comprises a leaf spring one end of which is fixed and the opposite end having thereon said nib which bears against all said levers.
 6. A mechanism according to claim 1 wherein said rotor is shaped to define recesses forming said elements.
 7. A mechanism according to claim 5 wherein said rotor is shaped to define recesses forming said elements and an extremity of each said lever has a return bent portion for engaging a corresponding recess in said rotor.
 8. A mechanism according to claim 1 including means frictionally mounting said rotor to said shaft.
 9. A mechanism according to claim 1 including a plurality of rotors, each having groups of elements thereon, the elements in each group being positioned to define a different code word and the groups being positioned about said rotor at different angular positions, and a plurality of groups of mechanical feelers, each group being associated with a different rotor; wherein said setting means includes a plurality of setting members, one for each member of a group of mechanical feelers and means for moving said setting means past each group of mechanical feelers to set the members in each group into predetermined positions for engaging elements on the associated rotor representing a selected code word.
 10. A mechanism accordinG to claim 9 wherein said mechanical feelers comprise levers and including means mounting said setting members to engage one end of said levers to move them from a first to a second position.
 11. A mechanism according to claim 10 wherein said mounting means includes means for setting said mechanical feelers prior to them being set by said levers.
 12. A mechanism according to claim 9 including a plurality of electric solenoids, having armatures each coupled to a different one of said setting members, and means for energising said solenoids in different combinations corresponding to different code words to cause said setting members to set the mechanical feelers in a group to predetermined positions to represent a selected code word. 